Of course it's never about that. Buyers, collectors, galleries, etc, certainly could care less whether you shot your great image with Tri-X or FP4, developed in Rodinal or any other concoction. The ones who constantly worry and obsess about such things are the ones who are hopelessly in the search of "something" to elevate their photography, and of course they are looking in the wrong places. As far as Salgado's way of shooting, well, that's his style. Some people would call it exploiting and others call it getting close to the subject. Personally, if your job is to photograph and sell prints, the Salgado approach leaves me a bit uncomfortable. At the end of the day, you are engaging, befriending, smiling with one purpose in mind: take good pictures and making art for your own benefit. Of course there are exceptions but again, the thought of engaging strangers for a while, with the intent of simply taking their pictures and then leave, doesn't give me a good feeling. I've done it, I may still do it, but I do not enjoy it. The other side, which some call "voyeurism" , and what pretty much was Bresson's method, is to be a ghost. It really comes down to one's personality, values, and needs. In the end, do what you are comfortable doing and create your own style/voice around it. Forcing oneself to be different, to emulate someone else, is not always the best answer.